Hydraulic valve lifters and solid valve lifters, for use in internal combustion engines, are well known in the engine art. A valve lifter of this type, engaging a camshaft lobe at one end and a push-rod or valve stem at the other end, slides reciprocally in a bore of the engine block. The lifter, typically assembled from the top side of the engine block, engages a camshaft lobe via a camshaft follower end which preferably includes a roller. Unless suitably constrained by an anti-rotation guide, a roller follower lifter may rotate axially in its bore during reciprocation, thereby undesirably misaligning its roller follower from the associated cam lobe.
Lifter anti-rotation guides in the prior art are positioned on and secured to the top side surface of the engine block adjacent the lifter bore. When fastened to the engine block above the lifter, a closely-fitting aperture in the anti-rotation guide snuggly surrounds an end of the lifter exposed above the engine block opposite the roller follower end. A locating feature in the guide aperture, such as a flat or a keyway, mates with a similar feature in the lifter to prevent the lifter from rotating about its longitudinal axis during reciprocation. Since the prior art anti-rotation guide resides above the block and occupies significant space, it may interfere with other engine components such as the cylinder head and intake manifold. Typically, a lifter is installed into its bore from the top side of the engine, and the anti-rotation guide is attached to the engine following lifter installation.
However, in some engines where the camshaft is embedded deeply inside the engine block, it is not possible for the lifters to be assembled from the top side of the block, and it may even be undesirable for an end of the lifter to be exposed above the block to be gripped by an anti-rotation guide installed on the top of the block as in the prior art. In such engines, the lifters must be installed from the bottom side of an engine block. Because of space constraints on the bottom side of an engine block, a conventional, externally mounted anti-rotation aperture guide cannot be readily adapted for use on the bottom side of the block.
Therefore, what is needed in the art is a compact anti-rotation guide that fits inside an engine block as a non-rotatable sleeve between a lifter body and a lifter bore.
What is further needed in the art is a compact anti-rotation guide that can be assembled into an engine from the bottom side, or camshaft side, of an engine block.
What is further needed in the art is a compact anti-rotation guide that can be assembled into an engine block before the corresponding valve lifter is installed.
What is still further needed in the art is a compact anti-rotation guide that also permits oil to flow to a lash-control element of a hydraulic valve lifter.
What is still further needed in the art is a compact anti-rotation guide-element comprising a plurality of individual anti-rotation guides, the element being kittable in a pre-assembly step.
It is a principal object of the present invention to provide lifter anti-rotation means that permits installation of a valve lifter from the bottom side of an engine block.